The present invention relates to a lighting system and a display.
As disclosed in Japanese Laid-Open Patent Publication No. 10-78582, a typical lighting system having light emitting elements is used as a backlight in a liquid crystal display. A liquid crystal display 50 shown in FIG. 8 includes a lighting panel 52 and a liquid crystal panel 51. The liquid crystal panel 51 shows an image using light from the lighting panel 52. The lighting panel 52 is formed by laminating a cathode 54, an electroluminescent layer 55, and an anode 56 in this order on a substrate 53. The cathode 54 is reflective. The electroluminescent layer 55 functions as a light emitting element. The anode 56 is transmissive.
In low light, the liquid crystal display 50 shows an image using light emitted by the electroluminescent layer 55. Light emitted by the electroluminescent layer 55 passes through the interface 57 between the electroluminescent layer 55 and the anode 56 and exits from a light outputting surface of the lighting panel 52 that faces the liquid crystal panel 51. In bright light, the liquid crystal display 50 shows an image using outside light. Outside light that enters the lighting panel 52 through the light outputting surface is reflected by the cathode 54. The reflected outside light passes through the interface 57 and exits from the light outputting surface.
Light emitted by the electroluminescent layer 55 is irradiated in all directions. That is, the light is not only irradiated toward the cathode 54 and the anode 56, but also irradiated in a direction parallel to the interface 57.
Light irradiated in a direction parallel to the interface 57 is converted into thermal energy while being propagated through the electroluminescent layer 55 or leaks from portions of the lighting panel 52 other than the light outputting surface. As a result, the light does not pass through the interface 57. Also, light that has a great incident angle relative to the interface 57 does not pass through but is totally reflected by the interface 57. The reflected light is converted into thermal energy while being propagated through the electroluminescent layer 55 or leaks from portions of the lighting panel 52 other than the light outputting surface.
In this manner, part of the light emitted by the electroluminescent layer 55 does not exit from the light outputting surface. In other words, part of the light emitted by the electroluminescent layer 55 is not used for showing an image and is wasted.